1. Field of the Invention
This invention relates to door closures and, more particularly, to apparatus for automatically closing either door of a pair of sliding doors.
2. Description of the Prior Art
To enjoy widespread use, an automatic closure for sliding doors must include several features. First, the closure must be sufficiently rugged to withstand wear due to use in commercial environments. Second, it must be simple in construction and easy to install so that persons who do not possess great skill with tools can install it themselves. Finally, where it is desirable to conceal the closure from view, for example where the sliding doors are used in residential closets, a user must be able to open and close the doors without manually manipulating the closure.
Sliding door closures using counterweights or electric motors enjoy only limited use because they are relatively expensive and difficult to install. Closures having systems of levers have long been used to manually or automatically close sliding elevator doors. Examples of such closures are disclosed in U.S. Pat. Nos. 1,204,913; 1,714,761; 1,203,413; 1,585,666; and 1,620,430. However, an objective of such closures is to lock the door in the closed position. Thus, the lever systems of such closures require that the longitudinal axes of the levers be aligned when the door reaches the closed position. The door can be reopened only by an operator inside the elevator who breaks the lock by moving the levers out of longitudinal alignment. Accordingly, such closures must be accessible to an operator for manual manipulation. Moreover, such closures generally are adapted to open only one door.
Examples of other door closures using lever systems are disclosed in U.S. Pat. Nos. 1,201,313; 2,723,848; 3,561,161; and 544,667.
Therefore a need exists for a closure that can automatically close either door of a pair of sliding doors, that is relatively simple, inexpensive, and easy to install, and that allows a user to open and close the door operated by the closure without manually manipulating the closure.